Study On Electrochemiluminescence And Biosensing Based On New Composite Nanomaterial

In recent years,with the rapid development of nanotechnology,the utility of nanomaterials for enhancing the ECL responses have been used in the ECL biosensing field.Electrochemiluminescence?ECL?and electrochemical analysis are regarded as simple,sensitive,and powerful analytical techniques triggered by an electrochemical reaction.As powerful analytical methods,ECL and electrochemical analysis has gained special attention of the researchers due to their low background signals,wide linear range,high sensitivity,good selectivity,simple operation and low cost and so on.In this paper,we mainly studied the preparation of many new composite nanomaterials,and successfully used them in ECL and electrochemical biosensing for highly sensitive detection of thrombin,CEA and Hg²⁺ by target recycling amplification strategy.The major contents of this thesis were studied as follows:1.A novel silver nanoclusters?AgNCs?were in situ synthesized and used as versatile electrochemiluminescence?ECL?and electrochemical?EL?signal probes for amplified detection of thrombin by using DNAzyme-assisted target recycling and hybridization chain reaction?HCR?multiple amplification strategy.The presence of target thrombin firstly opened the hairpin DNA,followed by DNAzyme-catalytic recycling cleavage of excess substrates,which could generate large number of substrate fragments?s1?.Then these s1 fragments were captured by SH-DNA on the Au nanoparticle-modified electrode,which further triggered the subsequent HCR of the hairpin DNA probes.The numerous AgNCs were in situ synthesized by incubation the dsDNA template-modified electrode with AgNO₃ and sodium borohydride.By integrating the DNAzyme recycling and HCR dual amplification strategy,the amount of AgNCs is dramatically enhanced,leading to substantially amplified ECL and electrochemical current signal responses for highly sensitive detection of thrombin.Importantly,this design is promising to be extended to provide a highly sensitive platform for various target biomolecules.2.A novel Ru?bpy?₃²⁺-doped SiO₂ nanocomposite was prepared,and used as ECL signal probe to develop an ECL biosensor for sensitive detection of CEA based on efficient ECL quenching by ferrocene using target recycling amplification strategy.The core-shell Au@Fe3O4 magnetic bead?MB?was acted as a nanocarrier to immobilize Ru@SiO₂ signal probe by Au-S bond,then the ferrocene-labeled probe?Fc-probe?was linked to the magnetic bead for ECL quenching through DNA hybridization.Numerous DNA1 sequences were produced based on target recycling amplification and displaced the Fc-probe on the magnetic bead,leading to the ECL enhancement of the signal probe.The developed ECL biosensor displayed good sensitivity and high selectivity for CEA detection,the detection linear range was from 10 ng/m L to 10 fg/m L,and the detection limit was down to 2.3 fg/mL.3.We presented a nonlinear hybridization chain reaction?HCR?system in which a trigger DNA initiates the self-assembly of double-stranded DNA substrates into dendritic nanostructures with plenty of ECL probe.A novel ECL biosensor was constructed for high sensitive detection of Hg²⁺ based on Exonuclease III and endonuclease-assisted recycling amplification strategy.The biosensor showed high selectivity and low detection limit for Hg²⁺ detection,the detection linear range was from 100 fM to 50 nM,and the detection limit was 23.6 fM.The proposed ECL biosensor was potentially suitable for not only routine detection of Hg²⁺ in real environmental water samples,but also holds great promise for detecting various targets by changing H-DNA probe.